turunan pertama fungsi f(×)=X3 cos 2x

misal : u = x^3, u' = 3x^2, v = cos 2x, v'= -2sin2x

f'(x) = u'.v + u.v'
f'(x) = 3x^2 . cos 2x + x^3 . (-2sin2x)
f'(x) = 3x^2cos2x - 2x^3sin2x

f(x) = x^3 cos 2x = u . v
u = x^3 => u' = 3x^2
v = cos 2x => v' = -2 sin 2x
f'(x) = u' v + v' u
= 3x^2 . cos 2x + (-2 sin 2x) . x^3
= 3x^2 cos 2x - 2x^3 sin 2x

^ = pangkat